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Warkentin TE. Autoimmune Heparin-Induced Thrombocytopenia. J Clin Med 2023; 12:6921. [PMID: 37959386 PMCID: PMC10649402 DOI: 10.3390/jcm12216921] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 11/15/2023] Open
Abstract
Autoimmune thrombocytopenia (aHIT) is a severe subtype of heparin-induced thrombocytopenia (HIT) with atypical clinical features caused by highly pathological IgG antibodies ("aHIT antibodies") that activate platelets even in the absence of heparin. The clinical features of aHIT include: the onset or worsening of thrombocytopenia despite stopping heparin ("delayed-onset HIT"), thrombocytopenia persistence despite stopping heparin ("persisting" or "refractory HIT"), or triggered by small amounts of heparin (heparin "flush" HIT), most cases of fondaparinux-induced HIT, and patients with unusually severe HIT (e.g., multi-site or microvascular thrombosis, overt disseminated intravascular coagulation [DIC]). Special treatment approaches are required. For example, unlike classic HIT, heparin cessation does not result in de-escalation of antibody-induced hemostasis activation, and thus high-dose intravenous immunoglobulin (IVIG) may be indicated to interrupt aHIT-induced platelet activation; therapeutic plasma exchange may be required if high-dose IVIG is ineffective. Also, aHIT patients are at risk for treatment failure with (activated partial thromboplastin time [APTT]-adjusted) direct thrombin inhibitor (DTI) therapy (argatroban, bivalirudin), either because of APTT confounding (where aHIT-associated DIC and resulting APTT prolongation lead to systematic underdosing/interruption of DTI therapy) or because DTI inhibits thrombin-induced protein C activation. Most HIT laboratories do not test for aHIT antibodies, contributing to aHIT under-recognition.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine and Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada; ; Tel.: +1-(905)-527-0271 (ext. 46139)
- Service of Benign Hematology, Hamilton Health Sciences (General Site), Hamilton, ON L8L 2X2, Canada
- Transfusion Medicine, Hamilton Regional Laboratory Medicine Program, Hamilton, ON L8L 2X2, Canada
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Warkentin TE. Platelet-activating anti-PF4 disorders: an overview. Semin Hematol 2022; 59:59-71. [DOI: 10.1053/j.seminhematol.2022.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 11/11/2022]
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Datta P, Zhang F, Dordick JS, Linhardt RJ. Platelet factor 4 polyanion immune complexes: heparin induced thrombocytopenia and vaccine-induced immune thrombotic thrombocytopenia. Thromb J 2021; 19:66. [PMID: 34526009 PMCID: PMC8443112 DOI: 10.1186/s12959-021-00318-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 09/01/2021] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND This is a review article on heparin-induced thrombocytopenia, an adverse effect of heparin therapy, and vaccine-induced immune thrombotic thrombocytopenia, occurring in some patients administered certain coronavirus vaccines. MAIN BODY/TEXT Immune-mediated thrombocytopenia occurs when specific antibodies bind to platelet factor 4 /heparin complexes. Platelet factor 4 is a naturally occurring chemokine, and under certain conditions, may complex with negatively charged molecules and polyanions, including heparin. The antibody-platelet factor 4/heparin complex may lead to platelet activation, accompanied by other cascading reactions, resulting in cerebral sinus thrombosis, deep vein thrombosis, lower limb arterial thrombosis, myocardial infarction, pulmonary embolism, skin necrosis, and thrombotic stroke. If untreated, heparin-induced thrombocytopenia can be life threatening. In parallel, rare incidents of spontaneous vaccine-induced immune thrombotic thrombocytopenia can also occur in some patients administered certain coronavirus vaccines. The role of platelet factor 4 in vaccine-induced thrombosis with thrombocytopenia syndrome further reinforces the importance the platelet factor 4/polyanion immune complexes and the complications that this might pose to susceptible individuals. These findings demonstrate, how auxiliary factors can complicate heparin therapy and drug development. An increasing interest in biomanufacturing heparins from non-animal sources has driven a growing interest in understanding the biology of immune-mediated heparin-induced thrombocytopenia, and therefore, the development of safe and effective biosynthetic heparins. SHORT CONCLUSION In conclusion, these findings further reinforce the importance of the binding of platelet factor 4 with known and unknown polyanions, and the complications that these might pose to susceptible patients. In parallel, these findings also demonstrate how auxiliary factors can complicate the heparin drug development.
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Affiliation(s)
- Payel Datta
- Heparin Applied Research Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Fuming Zhang
- Heparin Applied Research Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Jonathan S Dordick
- Heparin Applied Research Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Robert J Linhardt
- Heparin Applied Research Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
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Abstract
Heparin-induced thrombocytopenia (HIT) is an immune-mediated condition causing thrombocytopenia and paradoxical thrombosis after exposure to heparin or low-molecular-weight heparin. It has been rarely reported by Fondaparinux, an artificial pentasaccharide similar to heparin. This manuscript presents a case of HIT associated with fondaparinux use.
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Affiliation(s)
- Jahanzeb Malik
- Dr. Jahanzeb Malik, Rawalpindi Institute of Cardiology, Rawalpindi, Pakistan
| | - Nismat Javed
- Dr. Nismat Javed, Shifa College of Medicine, Shifa Tameer-e-Millat University, Islamabad, Pakistan
| | - Matiullah Kamin
- Dr. Matiullah Kamin, Shifa International Hospital, Islamabad, Pakistan
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Cai Z, Greene MI, Zhu Z, Zhang H. Structural Features and PF4 Functions that Occur in Heparin-Induced Thrombocytopenia (HIT) Complicated by COVID-19. Antibodies (Basel) 2020; 9:E52. [PMID: 33050376 PMCID: PMC7709132 DOI: 10.3390/antib9040052] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/10/2020] [Accepted: 09/29/2020] [Indexed: 01/08/2023] Open
Abstract
Platelet factor 4 (PF4, CXCL4) is a small chemokine protein released by activated platelets. Although a major physiological function of PF4 is to promote blood coagulation, this cytokine is involved in innate and adaptive immunity in events when platelets are activated in response to infections. Coronavirus disease 2019 (COVID-19) patients have abnormal coagulation activities, and severe patients develop higher D-dimer levels. D-dimers are small protein products present in the blood after blood clots are degraded by fibrinolysis. To prevent clotting, heparin is often clinically used in COVID-19 patients. Some clinical procedures for the management of COVID-19 patients may include extracorporeal membrane oxygenation (ECMO) and renal replacement therapy (CRRT), which also require the use of heparin. Anti-PF4 antibodies are frequently detected in severe patients and heparin-induced thrombocytopenia (HIT) can also be observed. PF4 and its role in HIT as well as in pathologies seen in COVID-19 patients define a potential therapeutic option of using blocking antibodies in the treatment of COVID-19.
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Affiliation(s)
| | | | | | - Hongtao Zhang
- Departments of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19301, USA; (Z.C.); (M.I.G.); (Z.Z.)
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Houlden RL, Janmohamed A. BILATERAL ADRENAL HEMORRHAGE WITH ADRENAL INSUFFICIENCY AFTER DALTEPARIN USE POST HIP ATHROPLASTIES. AACE Clin Case Rep 2020; 6:e141-e143. [PMID: 32524029 DOI: 10.4158/accr-2019-0434] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 02/12/2020] [Indexed: 11/15/2022] Open
Abstract
Objective Multiple case reports have implicated the use of heparin for deep vein thrombosis (DVT) prophylaxis with bilateral adrenal hemorrhage. Only 1 previous report has described this with the low molecular weight product, dalteparin. We report a case following bilateral hip arthroplasties. Methods Clinical and laboratory data are presented. Results A 69-year-old woman underwent bilateral total hip arthroplasties with dalteparin 5,000 international units subcutaneously daily for 30 days postoperatively. The patient's past medical history was unremarkable. She was discharged 5 days post-surgery and required readmission 1 day later for epigastric pain, nausea, and vomiting. Her platelet count was 91 × 109/L (normal, 150 to 400 × 109/L). She was discharged after 4 days with pain resolution. She presented 4 weeks later with nausea and vomiting for several days. Serum sodium was 123 mmol/L (normal, 133 to 145 mmol/L), potassium was 6.0 mmol/L (normal, 3.7 to 5.3 mmol/L), total calcium was 3.37 mmol/L (normal, 2.25 to 2.80 mmol/L), creatinine was 404 μmol/L (normal, 0 to 85 μmol/L), and her platelet count was normal. On short adrenocorticotropic hormone stimulation test, baseline plasma cortisol was 123 nmol/L and the peak was 129 nmol/L. She was treated with hydrocortisone, fludrocortisone, and 0.9% saline with resolution of symptoms and normalization of electrolytes, calcium, and renal function. Computed tomography showed bilateral adrenal masses. Core needle biopsy was consistent with necrosis. There were no bleeding disorders on hematologic work 3 months later. The most likely etiology of bilateral adrenal hemorrhage was heparin-induced thrombocytopenia from dalteparin. Conclusion This case highlights the importance of vigilance for the complication of bilateral adrenal hemorrhage with adrenal insufficiency in patients receiving dalteparin for DVT prophylaxis.
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Greinacher A, Selleng K, Warkentin TE. Autoimmune heparin-induced thrombocytopenia. J Thromb Haemost 2017; 15:2099-2114. [PMID: 28846826 DOI: 10.1111/jth.13813] [Citation(s) in RCA: 280] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Indexed: 01/18/2023]
Abstract
Autoimmune heparin-induced thrombocytopenia (aHIT) indicates the presence in patients of anti-platelet factor 4 (PF4)-polyanion antibodies that are able to activate platelets strongly even in the absence of heparin (heparin-independent platelet activation). Nevertheless, as seen with serum obtained from patients with otherwise typical heparin-induced thrombocytopenia (HIT), serum-induced platelet activation is inhibited at high heparin concentrations (10-100 IU mL-1 heparin). Furthermore, upon serial dilution, aHIT serum will usually show heparin-dependent platelet activation. Clinical syndromes associated with aHIT include: delayed-onset HIT, persisting HIT, spontaneous HIT syndrome, fondaparinux-associated HIT, heparin 'flush'-induced HIT, and severe HIT (platelet count of < 20 × 109 L-1 ) with associated disseminated intravascular coagulation (DIC). Recent studies have implicated anti-PF4 antibodies that are able to bridge two PF4 tetramers even in the absence of heparin, probably facilitated by non-heparin platelet-associated polyanions (chondroitin sulfate and polyphosphates); nascent PF4-aHIT-IgG complexes recruit additional heparin-dependent HIT antibodies, leading to the formation of large multimolecular immune complexes and marked platelet activation. aHIT can persist for several weeks, and serial fibrin, D-dimer, and fibrinogen levels, rather than the platelet count, may be helpful for monitoring treatment response. Although standard anticoagulant therapy for HIT ought to be effective, published experience indicates frequent failure of activated partial thromboplastin time (APTT)-adjusted anticoagulants (argatroban, bivalirudin), probably because of underdosing in the setting of HIT-associated DIC, known as 'APTT confounding'. Thus, non-APTT-adjusted therapies with drugs such as danaparoid and fondaparinux, or even direct oral anticoagulants, such as rivaroxaban or apixaban, are suggested therapies, especially for long-term management of persisting HIT. In addition, emerging data indicate that high-dose intravenous immunoglobulin can interrupt HIT antibody-induced platelet activation, leading to rapid platelet count recovery.
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MESH Headings
- Administration, Oral
- Animals
- Anticoagulants/administration & dosage
- Anticoagulants/adverse effects
- Anticoagulants/immunology
- Autoantibodies/blood
- Autoimmunity/drug effects
- Blood Coagulation/drug effects
- Blood Platelets/drug effects
- Blood Platelets/immunology
- Blood Platelets/metabolism
- Heparin/adverse effects
- Heparin/immunology
- Humans
- Immunoglobulins, Intravenous/administration & dosage
- Immunologic Factors/administration & dosage
- Partial Thromboplastin Time
- Platelet Activation/drug effects
- Platelet Factor 4/immunology
- Purpura, Thrombocytopenic, Idiopathic/blood
- Purpura, Thrombocytopenic, Idiopathic/chemically induced
- Purpura, Thrombocytopenic, Idiopathic/drug therapy
- Purpura, Thrombocytopenic, Idiopathic/immunology
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Affiliation(s)
- A Greinacher
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - K Selleng
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - T E Warkentin
- Department of Pathology and Molecular Medicine, Department of Medicine, and McMaster Centre for Transfusion Research, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
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Minet V, Dogné JM, Mullier F. Functional Assays in the Diagnosis of Heparin-Induced Thrombocytopenia: A Review. Molecules 2017; 22:molecules22040617. [PMID: 28398258 PMCID: PMC6153750 DOI: 10.3390/molecules22040617] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 04/05/2017] [Accepted: 04/08/2017] [Indexed: 01/09/2023] Open
Abstract
A rapid and accurate diagnosis in patients with suspected heparin-induced thrombocytopenia (HIT) is essential for patient management but remains challenging. Current HIT diagnosis ideally relies on a combination of clinical information, immunoassay and functional assay results. Platelet activation assays or functional assays detect HIT antibodies that are more clinically significant. Several functional assays have been developed and evaluated in the literature. They differ in the activation endpoint studied; the technique or technology used; the platelet donor selection; the platelet suspension (washed platelets, platelet rich plasma or whole blood); the patient sample (serum or plasma); and the heparin used (type and concentrations). Inconsistencies in controls performed and associated results interpretation are common. Thresholds and performances are determined differently among papers. Functional assays suffer from interlaboratory variability. This lack of standardization limits the evaluation and the accessibility of functional assays in laboratories. In the present article, we review all the current activation endpoints, techniques and methodologies of functional assays developed for HIT diagnosis.
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Affiliation(s)
- Valentine Minet
- Department of Pharmacy, Namur Thrombosis and Hemostasis Center (NTHC), Namur Research Institute for LIfe Sciences (NARILIS), University of Namur, Namur 5000, Belgium.
| | - Jean-Michel Dogné
- Department of Pharmacy, Namur Thrombosis and Hemostasis Center (NTHC), Namur Research Institute for LIfe Sciences (NARILIS), University of Namur, Namur 5000, Belgium.
| | - François Mullier
- CHU UCL Namur, Namur Thrombosis and Hemostasis Center (NTHC), Hematology Laboratory, Université catholique de Louvain, Yvoir 5530, Belgium.
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10
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Warkentin TE. Clinical picture of heparin-induced thrombocytopenia (HIT) and its differentiation from non-HIT thrombocytopenia. Thromb Haemost 2016; 116:813-822. [PMID: 27656712 DOI: 10.1160/th16-06-0435] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/12/2016] [Indexed: 12/14/2022]
Abstract
HIT is an acquired antibody-mediated disorder strongly associated with thrombosis, including microthrombosis secondary to disseminated intravascular dissemination (DIC). The clinical features of HIT are reviewed from the perspective of the 4Ts scoring system for HIT, which emphasises its characteristic timing of onset of thrombocytopenia. HIT antibodies recognize multimolecular complexes of platelet factor 4 (PF4)/heparin. However, a subset of HIT sera recognise PF4 bound to platelet chondroitin sulfate; these antibodies activate platelets in vitro and in vivo even in the absence of heparin, thus explaining: delayed-onset HIT (where HIT begins or worsens after stopping heparin); persisting HIT (where HIT takes several weeks to recover); spontaneous HIT syndrome (a disorder clinically and serologically resembling HIT but without proximate heparin exposure); and fondaparinux-associated HIT (four distinct syndromes featuring thrombocytopenia that begins or worsens during treatment with fondaparinux), with a new patient case presented with ongoing thrombocytopenia (and fatal haemorrhage) during treatment of HIT with fondaparinux, with fondaparinux-dependent platelet activation induced by patient serum ("fondaparinux cross-reactivity"). Ironically, despite existence of fondaparinux-associated HIT, this pentasaccharide anticoagulant is a frequent treatment for HIT (including one used by the author). HIT can be confused with other disorders, including those with a) timing similar to HIT (e. g. abciximab-associated thrombocytopenia of delayed-onset); b) combined thrombocytopenia/thrombosis (e. g. symmetrical peripheral gangrene secondary to acute DIC and shock liver); and c) both timing of onset and thrombosis (e. g. warfarin-associated venous limb gangrene complicating cancer-associated DIC). By understanding clinical and pathophysiological similarities and differences between HIT and non-HIT mimicking disorders, the clinician is better able to make the correct diagnosis.
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Affiliation(s)
- Theodore E Warkentin
- Prof. Theodore (Ted) E. Warkentin, Hamilton Regional Laboratory Medicine Program, Room 1-270B, Hamilton General Hospital, 237 Barton St. E., Hamilton, Ontario L8L 2X2, Canada, Tel.: +1 905 527 0271 ext. 46139, Fax: +1 905 577 1421, E-mail:
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11
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Bakchoul T. An update on heparin-induced thrombocytopenia: diagnosis and management. Expert Opin Drug Saf 2016; 15:787-97. [DOI: 10.1517/14740338.2016.1165667] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Tamam Bakchoul
- Institute for Immunology and Transfusion Medicine, Universitätsmedizin Greifswald, Greifswald, Germany
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12
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Smythe MA, Priziola J, Dobesh PP, Wirth D, Cuker A, Wittkowsky AK. Guidance for the practical management of the heparin anticoagulants in the treatment of venous thromboembolism. J Thromb Thrombolysis 2016; 41:165-86. [PMID: 26780745 PMCID: PMC4715846 DOI: 10.1007/s11239-015-1315-2] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Venous thromboembolism (VTE) is a serious and often fatal medical condition with an increasing incidence. Despite the changing landscape of VTE treatment with the introduction of the new direct oral anticoagulants many uncertainties remain regarding the optimal use of traditional parenteral agents. This manuscript, initiated by the Anticoagulation Forum, provides clinical guidance based on existing guidelines and consensus expert opinion where guidelines are lacking. This specific chapter addresses the practical management of heparins including low molecular weight heparins and fondaparinux. For each anticoagulant a list of the most common practice related questions were created. Each question was addressed using a brief focused literature review followed by a multidisciplinary consensus guidance recommendation. Issues addressed included initial anticoagulant dosing recommendations, recommended baseline laboratory monitoring, managing dose adjustments, evidence to support a relationship between laboratory tests and meaningful clinical outcomes, special patient populations including extremes of weight and renal impairment, duration of necessary parenteral therapy during the transition to oral therapy, candidates for outpatient treatment where appropriate and management of over-anticoagulation and adverse effects including bleeding and heparin induced thrombocytopenia. This article concludes with a concise table of clinical management questions and guidance recommendations to provide a quick reference for the practical management of heparin, low molecular weight heparin and fondaparinux.
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Affiliation(s)
| | | | - Paul P Dobesh
- University of Nebraska Medical Center College of Pharmacy, Omaha, NE, USA
| | | | - Adam Cuker
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ann K Wittkowsky
- University of Washington School of Pharmacy, 1959 NE Pacific St Box 356015, Seattle, WA, 98195, USA.
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Joglekar M, Khandelwal S, Cines DB, Poncz M, Rauova L, Arepally GM. Heparin enhances uptake of platelet factor 4/heparin complexes by monocytes and macrophages. J Thromb Haemost 2015; 13:1416-27. [PMID: 25960020 PMCID: PMC4516590 DOI: 10.1111/jth.13003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/23/2015] [Indexed: 01/17/2023]
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is an iatrogenic complication of heparin therapy caused by antibodies to a self-antigen, platelet factor (4) and heparin. The reasons why antibodies form to PF4/heparin, but not to PF4 bound to other cellular glycosaminoglycans are poorly understood. OBJECTIVE To investigate differences in cellular responses to cell-bound PF4 and PF4/heparin complexes, we studied the internalization of each by peripheral blood-derived monocytes, dendritic cells and neutrophils. METHODS AND RESULTS Using unlabeled and fluorescently-labeled antigen and/or labeled monoclonal antibody to PF4/heparin complexes (KKO), we show that PF4/heparin complexes are taken up by monocytes in a heparin-dependent manner and are internalized by human monocytes and dendritic cells, but not by neutrophils. Complexes of PF4/low-molecular-weight heparin and complexes composed of heparin and murine PF4, protamine or lysozyme are internalized similarly, suggesting a common endocytic pathway. Uptake of complexes is mediated by macropinocytosis, as shown by inhibition using cytochalasin D and amiloride. Internalized complexes are transported intact to late endosomes, as indicated by co-staining of vesicles with KKO and lysosomal associated membrane protein-2 (LAMP-2). Lastly, we show that cellular uptake is accompanied by expression of MHCII and CD83 co-stimulatory molecules. CONCLUSIONS Taken together, these studies establish a distinct role for heparin in enhancing antigen uptake and activation of the initial steps in the cellular immune response to PF4-containing complexes.
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Affiliation(s)
- M Joglekar
- Division of Hematology, Duke University Medical Center, Durham, NC, USA
| | - S Khandelwal
- Division of Hematology, Duke University Medical Center, Durham, NC, USA
| | - D B Cines
- Department of Pathology and Laboratory Medicine, Perelman-University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - M Poncz
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - L Rauova
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - G M Arepally
- Division of Hematology, Duke University Medical Center, Durham, NC, USA
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14
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Serological investigation of patients with a previous history of heparin-induced thrombocytopenia who are reexposed to heparin. Blood 2014; 123:2485-93. [DOI: 10.1182/blood-2013-10-533083] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Key Points
Heparin rechallenge despite prior HIT often induces platelet-activating anti-PF4/heparin antibodies but no faster than seen with typical HIT. Risk of HIT recurring after heparin rechallenge is low but possible if IgG with heparin-independent platelet-activating properties are made.
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15
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Tandon VR, Sharma S, Mahajan S, Mahajan A, Khajuria V. A rare case of fondaparinux-induced major bleeding in postmenopausal woman prescribed for non-ST segment elevation Ml. J Midlife Health 2014; 4:241-3. [PMID: 24381468 PMCID: PMC3872673 DOI: 10.4103/0976-7800.122260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Fondaparinux sodium is a synthetic, sulfated pentasaccharide, selective factor Xa inhibitor, a safe and effective antithrombotic agent indicated for preventing thrombus formation in patients with acute coronary syndromes, including those with ST-segment elevation myocardial infarction (STEMI), non-STEMI (NSTEMI), or unstable angina. Major bleeding is rarely known to exist with the use of fondaparinux and to best of our knowledge there exist no isolated case report presenting with fondaparinux-induced major bleeding prescribed for recently diagnosed NSTEMI. The case report highlights, a need for clinicians to have a sound understanding of anticoagulant pharmacology, dosing, toxicity, individualized approach, and predicting the risk of bleeding before they are prescribed to advancing age persons.
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Affiliation(s)
- Vishal R Tandon
- Postgraduate Department of Pharmacology and Therapeutic, Government Medical College, Jammu, Jammu and Kashmir, India
| | - Sudhaa Sharma
- Department of Obstetrics and Gynecology, Government Medical College, Jammu, Jammu and Kashmir, India
| | - Shagun Mahajan
- Department of Nephrology Super-specialty Hospital, Government Medical College, Jammu, Jammu and Kashmir, India
| | - Annil Mahajan
- Department of General Medicine, Government Medical College, Jammu, Jammu and Kashmir, India
| | - Vijay Khajuria
- Postgraduate Department of Pharmacology and Therapeutic, Government Medical College, Jammu, Jammu and Kashmir, India
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Burger CF, Schlesinger JJ. Intravenous warfarin and heparin-induced thrombocytopenia: making the diagnosis, management, modern monitoring, and multidisciplinary care. Ann Pharmacother 2013; 48:286-91. [PMID: 24259642 DOI: 10.1177/1060028013511060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE To describe the diagnosis, management, and monitoring of a patient with heparin-induced thrombocytopenia (HIT) with thrombosis and simultaneous bleeding risk treated with argatroban and transitioned to intravenous (IV) warfarin secondary to the inability to administer enteral medications. CASE SUMMARY A 71-year-old man was admitted to the surgical intensive care unit (SICU) following aortic valve repair, coronary artery bypass, and ascending aortic aneurysm repair. On postoperative day 9, he was found to have a pulmonary embolism, and therapeutic heparin was started. The following day, his platelet count was found to have dropped precipitously. HIT was diagnosed, heparin was discontinued, and argatroban was initiated. On postoperative day 22, anticoagulation was discontinued because of massive gastrointestinal bleeding. On postoperative day 35, multiple venous thromboses were found, and argatroban was restarted. The patient developed a high-output enterocutaneous fistula, eliminating the option of enteral route of medication administration. The multidisciplinary SICU team transitioned the patient from argatroban to IV warfarin for long-term anticoagulation. The international normalized ratio was monitored and remained therapeutic throughout his admission without further thrombotic complications. DISCUSSION HIT occurs when antibodies develop to heparin-platelet factor 4 complexes, causing simultaneous hypercoagulability and thrombocytopenia. It is diagnosed based on both clinical factors and laboratory testing. Treatment includes discontinuation of all forms of heparin; initiation of a nonheparin anticoagulant, such as argatroban; and transition to warfarin. CONCLUSIONS IV warfarin is a therapeutic option for patients with malabsorption issues. A multidisciplinary team in an intensive care setting optimizes cost-effective, patient-centered, and safe care.
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Bhatt VR, Aryal MR, Shrestha R, Armitage JO. Fondaparinux-associated heparin-induced thrombocytopenia. Eur J Haematol 2013; 91:437-41. [PMID: 23905719 DOI: 10.1111/ejh.12179] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2013] [Indexed: 01/20/2023]
Abstract
OBJECTIVES Large licensing trials did not find any association between the use of fondaparinux and the development of heparin-induced thrombocytopenia (HIT). Fondaparinux is in fact recommended as an option for the management of HIT. Since the first report of fondaparinux-associated HIT in 2007, additional reports have been published. However, the rarity of these cases, differences in case definition, and lack of larger case series have prevented better understanding of this disease. The objective of this study was to determine the clinical manifestations of fondaparinux-associated HIT, the predictive value of pretest probability (4Ts) scoring system, and the outcomes associated with current management. METHODS Using several search terms, we reviewed all cases of fondaparinux-associated HIT reported and indexed in PubMed till May 2013. All references were also checked for additional reports. We categorized the cases of fondaparinux-associated HIT as confirmed, probable, and possible based on our case definition. RESULTS A total of eight cases of fondaparinux-associated HIT were identified. Fondaparinux-associated HIT occurred in the setting of pro-inflammatory state, prior HIT, or exposure to heparin products. Bilateral adrenal hemorrhage or infarct, reflecting hypercoagulability or disseminated intravascular coagulation, was seen in 25% of patients. The pretest probability (4Ts) scoring system used for HIT appears to correctly risk stratify all the cases. Although functional assays can be used for the diagnosis, in the presence of recent exposure to heparin products, only the demonstration of fondaparinux-dependent platelet activation should be considered confirmatory. Non-heparin anticoagulants are effective therapy; however, one-third of the patients had poor outcomes. CONCLUSION The risk of fondaparinux-associated HIT, although low is real, which along with documented cases of fondaparinux failure mandate its cautious use in the management of HIT.
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Affiliation(s)
- Vijaya R Bhatt
- Division of Hematology-Oncology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE
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Leporini C, Rende A, Sorrentino A, Rizzica E, Russo E, Gallelli L, De Sarro G. Efficacy and safety of off-label use of fondaparinux in the management of heparin-induced thrombocytopenia with thrombosis in an elderly woman. J Clin Pharmacol 2013; 53:999-1002. [PMID: 23832870 DOI: 10.1002/jcph.124] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 05/25/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Christian Leporini
- Centro Regionale di Informazione sul Farmaco, AO Mater Domini, Catanzaro, Italy
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Warkentin TE. HITlights: a career perspective on heparin-induced thrombocytopenia. Am J Hematol 2012; 87 Suppl 1:S92-9. [PMID: 22367928 DOI: 10.1002/ajh.23127] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 01/13/2012] [Accepted: 01/15/2012] [Indexed: 12/11/2022]
Abstract
Two decades of research into heparin-induced thrombocytopenia (HIT) permit a personal historical perspective on this fascinating syndrome. Previously, the frequency of HIT was unknown, although complicating thrombosis was believed to be rare and primarily arterial. The opportunity to apply a remarkable test for "HIT antibodies"--the (14) C-serotonin-release assay (SRA)--to serial plasma samples obtained during a clinical trial of heparin thromboprophylaxis, provided insights into the peculiar nature of HIT, such as, its prothrombotic nature--including its strong association with venous thrombosis (RR = 11.6 [95%CI, 6.4-20.8; P < 0.0001); its more frequent occurrence with unfractionated versus low-molecular-weight heparin; the "iceberg" model, which states that among the many patients who form anti-PF4/heparin antibodies during heparin therapy, only a minority whose antibodies evince strong platelet-activating properties develop HIT; and the characteristic HIT timeline, whereby serum/plasma antibodies are readily detectable at or prior to the HIT-associated platelet count fall. Applying the SRA also to patients encountered in clinical practice led to recognition of warfarin-induced venous limb gangrene (for which HIT is a major risk factor via its extreme hypercoagulability) and delayed-onset HIT (whereby thrombocytopenia begins or worsens following heparin discontinuation, due to the ability of HIT antibodies strongly to activate platelets even in the absence of heparin--so-called heparin-"independent" platelet activation). Recent concepts include the increasing recognition of HIT "overdiagnosis" (due to the low diagnostic specificity of the widely-applied PF4-dependent immunoassays), and the observation that HIT-associated consumptive coagulopathy is a risk factor for treatment failure with PTT-adjusted direct thrombin inhibitor therapy ("PTT confounding" secondary to HIT-associated coagulopathy).
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Affiliation(s)
- Theodore E Warkentin
- Department of Pathology and Molecular Medicine, Michael G DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.
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Linkins LA, Dans AL, Moores LK, Bona R, Davidson BL, Schulman S, Crowther M. Treatment and prevention of heparin-induced thrombocytopenia: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012; 141:e495S-e530S. [PMID: 22315270 DOI: 10.1378/chest.11-2303] [Citation(s) in RCA: 617] [Impact Index Per Article: 51.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is an antibody-mediated adverse drug reaction that can lead to devastating thromboembolic complications, including pulmonary embolism, ischemic limb necrosis necessitating limb amputation, acute myocardial infarction, and stroke. METHODS The methods of this guideline follow the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement. RESULTS Among the key recommendations for this article are the following: For patients receiving heparin in whom clinicians consider the risk of HIT to be > 1%, we suggest that platelet count monitoring be performed every 2 or 3 days from day 4 to day 14 (or until heparin is stopped, whichever occurs first) (Grade 2C). For patients receiving heparin in whom clinicians consider the risk of HIT to be < 1%, we suggest that platelet counts not be monitored (Grade 2C). In patients with HIT with thrombosis (HITT) or isolated HIT who have normal renal function, we suggest the use of argatroban or lepirudin or danaparoid over other nonheparin anticoagulants (Grade 2C). In patients with HITT and renal insufficiency, we suggest the use of argatroban over other nonheparin anticoagulants (Grade 2C). In patients with acute HIT or subacute HIT who require urgent cardiac surgery, we suggest the use of bivalirudin over other nonheparin anticoagulants or heparin plus antiplatelet agents (Grade 2C). CONCLUSIONS Further studies evaluating the role of fondaparinux and the new oral anticoagulants in the treatment of HIT are needed.
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Affiliation(s)
- Lori-Ann Linkins
- Department of Medicine, McMaster University, Hamilton, ON, Canada.
| | - Antonio L Dans
- College of Medicine, University of the Philippines Manila, Manila, Philippines
| | - Lisa K Moores
- The Uniformed Services, University of Health Sciences, Bethesda, MD
| | - Robert Bona
- School of Medicine, Quinnipiac University, North Haven, CT
| | | | - Sam Schulman
- Department of Medicine, McMaster University, Hamilton, ON, Canada
| | - Mark Crowther
- Department of Medicine, McMaster University, Hamilton, ON, Canada
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Fondaparinux - data on efficacy and safety in special situations. Thromb Res 2011; 129:407-17. [PMID: 22133273 DOI: 10.1016/j.thromres.2011.10.037] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/27/2011] [Accepted: 10/28/2011] [Indexed: 12/20/2022]
Abstract
New anticoagulants promise to have better efficacy, more safety and/or a better manageability than traditional anticoagulants. However, knowledge is limited regarding special situations such as renal insufficiency, obesity, pregnancy, long-term therapy, heparin-induced thrombocytopenia, treatment in patients with mechanical heart valves, use for children, and in patients with a high risk of thromboembolic complications. These situations have rarely or even never been the objective of randomised controlled trials. The purpose of the present article is to summarize and discuss available data on efficacy and safety in these special situations for one of the first new anticoagulants, the indirect factor-Xa inhibitor fondaparinux. Furthermore, we discuss safety in licensed indications and management of bleeding complications and comment on measuring of drug concentration in plasma.
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22
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Role of factor xa inhibitors in cancer-associated thrombosis: any new data? Adv Hematol 2011; 2011:196135. [PMID: 22013445 PMCID: PMC3195274 DOI: 10.1155/2011/196135] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 08/10/2011] [Accepted: 08/11/2011] [Indexed: 12/12/2022] Open
Abstract
The association between cancer and venous thromboembolism (VTE) has been well documented in the literature. Prevention and treatment of VTE in cancer patients is imperative. Typically, the mainstay regimen for VTE prevention and treatment has been anticoagulation therapy, unless contraindicated. This therapy consists of unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), factor Xa inhibitor, or vitamin K antagonist (VKA). Current guidelines recommend LMWH over VKA for the treatment of VTE in cancer patients. Factor-specific anticoagulants have been proven safe and effective, and recently factor Xa inhibitors have emerged as a treatment alternative to heparins and VKA. Currently, three factor Xa inhibitors have been identified: fondaparinux (the only one approved so far by the US Food and Drug Administration), idraparinux (in clinical trials), and idrabiotaparinux (in clinical trials). This paper will examine the role of these agents, focusing on fondaparinux, for the prevention and treatment of VTE in cancer patients.
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Miranda AC, Donovan JL, Tran MT, Gore JM. A case of unsuccessful treatment of heparin-induced thrombocytopenia (HIT) with fondaparinux. J Thromb Thrombolysis 2011; 33:133-5. [DOI: 10.1007/s11239-011-0641-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Fondaparinux cross-reacts with heparin antibodies in vitro in a patient with fondaparinux-related thrombocytopenia. Blood Coagul Fibrinolysis 2011; 22:76-8. [PMID: 21076279 DOI: 10.1097/mbc.0b013e328340ff24] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) related to fondaparinux has been rarely reported, although the ability of fondaparinux to cross-react with heparin antibodies has been often a subject of debate. A patient previously exposed to unfractionated heparin and low-molecular-weight heparin (LMWH) was diagnosed with HIT. During treatment with fondaparinux for 5 consecutive days, his thrombocytopenia significantly deteriorated. A functional platelet activation test in vitro showed clear platelet activation after serum exposure with fondaparinux. After discontinuation of fondaparinux, the platelet count was rapidly reestablished. Fondaparinux cross-reacted with heparin antibodies in this case of HIT, resulting in a deterioration of thrombocytopenia. The implication of this drug in HIT was observed clinically and demonstrated in vitro using a platelet activation test.
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Abstract
Heparin-induced thrombocytopenia (HIT) is an antibody-mediated prothrombotic disorder triggered by PF4-binding polyanions, usually heparin. The pentasaccharide anticoagulant, fondaparinux, despite its negative charge and structural similarity to heparin, does not usually promote antibody binding to PF4 (owing to absent/weak 'cross-reactivity'). Thus, despite its ability to trigger anti-PF4/heparin antibodies ('immunogenicity'), fondaparinux has low - but not zero - risk of inducing HIT de novo, or of exacerbating HIT when antibodies are already present. Indeed, despite rare reports of fondaparinux-induced HIT, this 'dissociation' between immunogenicity and cross-reactivity suggests that fondaparinux should be effective in treating HIT, as supported by several observational studies. An emerging issue: will clinicians accept this favorable experience of fondaparinux for treating HIT when a lack of randomized trials will hinder regulatory approval for this indication?
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Affiliation(s)
- Theodore E Warkentin
- Michael G DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.
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Successful use of fondaparinux in a patient with a mechanical heart valve replacement and a history of heparin-induced thrombocytopenia. J Thromb Thrombolysis 2011; 30:375-7. [PMID: 20571919 DOI: 10.1007/s11239-010-0494-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The development of heparin-induced thrombocytopenia (HIT) is an antibody-mediated clinicopathologic syndrome. The resultant thrombocytopenia and thrombosis can be severe and life-threatening. Fondaparinux is a parenteral factor Xa inhibitor used for venous thromboembolism prevention and treatment. Fondaparinux has minimal affinity for platelet factor 4, making it an alternative agent to unfractionated heparin (UFH) and low-molecular weight heparin (LMWH) and a plausible consideration for patients with a history of HIT. The use of fondaparinux in patients with mechanical heart valve replacement and a history of HIT has never been discussed in the literature. We report on the case of a patient with a mechanical aortic heart valve replacement and a history of HIT who was successfully bridged postoperatively with fondaparinux. While there is currently no literature to support the use of fondaparinux in patients with mechanical heart valves, this drug may offer an option for management of such patients who cannot use heparin products. However, further clinical investigations are warranted to confirm both the safety and efficacy of this agent in the mechanical heart valve population.
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Landenhed M, Johansson M, Erlinge D, Olsson ML, Bjursten H. Fondaparinux or enoxaparin: A comparative study of postoperative bleeding in coronary artery bypass grafting surgery. SCAND CARDIOVASC J 2009; 44:100-6. [DOI: 10.3109/14017430903388334] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Blackmer AB, Oertel MD, Valgus JM. Fondaparinux and the management of heparin-induced thrombocytopenia: the journey continues. Ann Pharmacother 2009; 43:1636-46. [PMID: 19737996 DOI: 10.1345/aph.1m136] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE To review the available literature addressing the role of fondaparinux in the management of heparin-induced thrombocytopenia (HIT). DATA SOURCES Primary articles were identified by a MEDLINE search (2004-June 2009) of English-language literature using the MeSH headings fondaparinux, heparin, low-molecular-weight heparin, and thrombocytopenia. Relevant consensus guidelines (2006-June 2009) were also identified. STUDY SELECTION AND DATA EXTRACTION All published studies and case reports, as well as relevant consensus guidelines, evaluating the use of fondaparinux for the management of HIT were included. DATA SYNTHESIS The role of fondaparinux in the management of HIT is a therapeutic controversy challenging clinicians today. An open-label, prospective pilot study of 7 patients with acute HIT supports fondaparinux as an alternative anticoagulant. Additionally, a total of 12 patients with HIT from a larger case study and retrospective cohort were successfully treated with fondaparinux. Much of the supporting data exists in the form of case reports, each demonstrating normalization of platelet counts without any evidence of new thrombosis. The differences in clinical scenarios as well as the role and dose of fondaparinux make interpretation of these reports difficult. Three case reports have been published raising concerns regarding fondaparinux causing or failing to manage HIT appropriately. However, common weaknesses such as small sample sizes and nonuniform definitions of HIT limit the usefulness of these findings. The updated American College of Chest Physicians consensus guidelines now recognize fondaparinux as an option in the management of HIT; however, the level of evidence supporting this is of low quality. The use of fondaparinux as a bridging agent between direct thrombin inhibitor and warfarin therapy has been proposed. A recently published case report gives support to this approach. CONCLUSIONS Controlled clinical trials evaluating the use of fondaparinux in the management of HIT need to be completed before this therapy can be routinely recommended.
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Affiliation(s)
- Allison Beck Blackmer
- Department of Pharmacy, The University of North Carolina Hospitals and Clinics, Chapel Hill, NC 27514, USA
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Abstract
Secondary thrombocytopenia is similar to primary or idiopathic thrombocytopenia (ITP) in that it is characterized by reduced platelet production or increased platelet destruction resulting in platelet levels<60,000/microL. Thrombocytopenia can occur from secondary causes associated with chronic disorders or with disturbed immune function due to chronic infections, lymphoproliferative and myeloproliferative disorders, pregnancy, or autoimmune disorders. Diagnosis of secondary ITP in some cases is complex, and the thrombocytopenia can often be resolved by treating the underlying disorder to the extent this is possible. In most cases, treatment is focused on reducing platelet destruction, but, in some cases, treatment may also be directed at stimulating platelet production. The most problematic cases of thrombocytopenia may be seen in pregnant women. This review will address various agents and their utility in treating ITP from secondary causes; in addition, thrombocytopenia in pregnancy, ITP in immunodeficiency conditions, and drug-induced thrombocytopenia will be discussed. Unlike primary ITP, treatment often must be tailored to the specific circumstance underlying the secondary ITP, even if the condition itself is incurable.
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Affiliation(s)
- James B Bussel
- Platelet Disorders Center, Division of Pediatric Hematology-Oncology, Weill Cornell Medical College of Cornell University, New York, NY 10021, USA.
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Current awareness: Pharmacoepidemiology and drug safety. Pharmacoepidemiol Drug Saf 2009. [DOI: 10.1002/pds.1647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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